Negotiations on devolution proposals for Norfolk, Suffolk and Cambridgeshire will not be re-opened, despite widespread concern about them, according to a government minister.

The warning came as MPs from across the region set out their concerns over the plan for a new combined authority for Norfolk, Suffolk and Cambridgeshire during a debate in Westminster this afternoon.

North West Norfolk MP Sir Henry Bellingham insisted he supported the idea of devolution.

But he said the proposal for a directly-elected mayor contained within the plan was a red line for him and warned the future of the whole deal could depend on it.

He said: “If the government insists on pushing this mayor proposal, I fear they will fail.”

Sir Henry reiterated his call for council and business leaders and police commissioners to form a regional committee, who would then elect their own chairman.

And Peterborough MP Stewart Jackson said there was little to unite communities in the three counties.

He asked: “Is there synergy between the Suffolk coast, St Neots, King’s Lynn, the city of Peterborough? I don’t think there is.”

He also voiced concerns over the potential for duplication of functions between the combined authority and existing tiers of government.

And he questioned why the deal proposed for East Anglia offered just £13 of funding per head of population compared to the £22 per head offered in the deal for the Sheffield city region.

But local government minister James Wharton confirmed there was no other deal available than the draft document signed by council leaders from the three counties last month.

He said: “We have made a deal. We want to deliver on that deal. We have no plans to re-open negotiations and start again.”

Mr Wharton described the deal as “exciting”, and said its geography had been agreed with the authorities involved.

But he reiterated that individual councils would not be forced to take part.

Jo Churchill, the MP for Bury St Edmunds, also argued that the potential benefits of the project, in areas such as housing and broadband, should not be overlooked.

She welcomed the appointment of Andy Wood as an independent chairman of the process and suggested council chiefs were starting to develop a shared vision following talks earlier in the day.

But shadow local government minister Emma Lewell-Buck claimed the deal was a “complete shambles”, because of the growing scale of local concern and the speed with which the plan is being pursued.

She said East Anglia was being given just seven months to agree its devolution deal, compared to a period of up to five years for Manchester’s deal.

She also described the idea of one mayor for three counties as an “unprecedented constituutional innovation” and claimed ministers had broken a pledge to councils to allow them to develop their own ideas.

She said: “This government has taken a heavy-handed, top down, dictatorial approach.”